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151.
Chaohai Wang Jeonghun Kim Jing Tang Jongbeom Na Yong‐Mook Kang Minjun Kim Hyunsoo Lim Yoshio Bando Jiansheng Li Yusuke Yamauchi 《Angewandte Chemie (International ed. in English)》2020,59(5):2066-2070
Carbon aerogels (CAs) with 3D interconnected networks hold promise for application in areas such as pollutant treatment, energy storage, and electrocatalysis. In spite of this, it remains challenging to synthesize high‐performance CAs on a large scale in a simple and sustainable manner. We report an eco‐friendly method for the scalable synthesis of ultralight and superporous CAs by using cheap and widely available agarose (AG) biomass as the carbon precursor. Zeolitic imidazolate framework‐8 (ZIF‐8) with high porosity is introduced into the AG aerogels to increase the specific surface area and enable heteroatom doping. After pyrolysis under inert atmosphere, the ZIF‐8/AG‐derived nitrogen‐doped CAs show a highly interconnected porous mazelike structure with a low density of 24 mg cm?3, a high specific surface area of 516 m2 g?1, and a large pore volume of 0.58 cm?3 g?1. The resulting CAs exhibit significant potential for application in the adsorption of organic pollutants. 相似文献
152.
153.
154.
Benzenetellurinyl trifluoromethanesulfonate in conjunction with acetonitrile readily effected amidotellurinylation reactions with alkynes. Most of the addition reactions proceeded in a trans fashion to form the (E)-β-acetamidovinyl phenyl telluroxides. Subsequently, it was found that the prevailing Markovnikov adducts from terminal alkynes immediately isomerized to (Z)-isomers which were isolated as the corresponding vinyltellurides. On the other hand, the adducts derived from internal alkynes thermally underwent a spontaneous intramolecular cyclization to be transformed eventually into oxazoles. 相似文献
155.
156.
Tokuyuki Kuroda Koji Hisamura Ikuo Matsukuma Hiroshi Nishikawa Makoto Morimoto Tadashi Ashizawa Nobuhiro Nakamizo Yoshio Otsuji 《Journal of heterocyclic chemistry》1992,29(5):1133-1142
Seventeen compounds having a variety of substituents at the 3- and 5′-positions of 2′-deoxy-5-fluorouridine (5-FUdR) and 5-fluorouridine (5-FUR) were synthesized, and their γ-radiolysis in aqueous solutions were studied. The compounds having thioureido (RNHCSNH, R H, PhCH2, acyl) and thiocarbonylamino (XCSNH, X PhCH2S, PhO) groups at the 3-position of 5-FUdR were efficiently cleaved to give 5-FUdR with high G values upon γ-irradiation of their aqueous solutions. The active species for these cleavage reactions were hydrated electron (e− aq), H• and HO•. However, the compounds having a dimethylsulfoxyimino group at 3-position of 5-FUdR and 5-FUR afforded 5-FUdR and 5-FUR only under the radiolysis conditions where e− aq becomes a principal active species. The compound having a 2-benzoylthiazoylthiocarbonylamino group at the 3-position of 5-FUdR showed the highest reactivity toward HO.. The mechanisms of these γ-radiolysis reactions are discussed. The examination of anticellular activities of γ-irradiated compounds having a thiocarbonylamino group at the 3-position of 5-FUdR toward murine Sarcoma 180 cells revealed that these compounds may be utilized as a candidate for a radiation-induced drug (RID). 相似文献
157.
Yoshio Okamoto 《Macromolecular Symposia》1996,101(1):343-354
This review mainly describes the asymmetric synthesis of optically active polymers with helical conformation. Bulky methacrylates such as triphenylmethyl methacrylate and 1-phenyldibenzosuberyl methacrylate give one-handed helical and optically active polymers with almost perfectly isotactic main chain conformation by polymerization with chiral anionic initiators. The radical polymerization and copolymerization of these monomers under chiral conditions also afford optically active polymers with prevailing one-handed helicity. N, N-Disubstituted acrylamides also give optically active, helical polymers in the asymmetric anionic polymerization. Optically active polyisocyanates with a prevailing one-handed helical structure have been prepared in the copolymerization of an achiral isocyanate with a small amount of an optically active isocyanate and also in the polymerization of alkyl and aromatic isocyanates with optically active lithium alkoxide or amide compounds. The existence of a stable helical structure for polychloral has been successfully proved with the helical oligomers of chloral. One-handed helical polyisocyanides have been prepared by helix-sense-selective polymerization of bulky isocyanides and also by the cyclopolymerization of a 1, 2-diisocyanobenzene derivative with the Pd complex of a one-handed helical oligomer. 相似文献
158.
159.
Yoshio Okamoto Tamaki Nakano Yoshifumi Shikisai Masatoshi Mori 《Macromolecular Symposia》1995,89(1):479-488
Stereospecific and asymmetric (helix-sense-selective) polymerization of 1-phenyldibenzosuberyl methacrylate (PDBSMA) was performed with radical and anionic initiators. A highly isotactic polymer having triad isotacticity greater than 97% was obtained by radical polymerization with (i-PrOCOO)2 at 40°C. The radical polymerization of PDBSMA in (+)- and (-)-menthol gave (-)-and (+)-polymers, respectively, whose optical activity is ascribed to the prevailing one-handed helical conformation of a polymer chain. The radical copolymerization of PDBSMA with a small amount of an optically active monomer, (+)-phenyl-2-pyridyl-o-tolylmethyl methacrylate, afforded an optically active copolymer with the prevailing one-handed helical structure of PDBSMA sequences. Asymmetric anionic polymerization of PDBSMA was carried out with the complex of N, N′-diphenylethylenediamine monolithium amide and a chiral ligand, (+)-1-(2-pyrrolidinylmethyl)pyrrolidine in toluene at −78°C. The obtained polymer was highly isotactic and optically active due to nearly 100% one-handed helical structure. 相似文献
160.
Yoshio Kobayashi Tsukasa Shirochi Takafumi Maeda Yusuke Yasuda Toshiaki Morita 《Surface and interface analysis : SIA》2013,45(9):1424-1428
This paper describes a metal–metal bonding technique using metallic Cu nanoparticles prepared in aqueous solution. A colloid solution of metallic Cu particles with a size of 54 ± 15 nm was prepared by reducing Cu2+ (0.01 M (CH3COO)2Cu) with hydrazine (0.6 M) in the presence of stabilizers (5 × 10?4 M citric acid and 5 × 10?3 M cetyltrimethylammonium bromide) in water at room temperature in air. Discs made of metallic materials (Cu, Ni/Cu, or Ag/Ni/Cu) were successfully bonded under annealing at 400 °C and pressurizing at 1.2 MPa for 5 min in H2 gas with help of the metallic Cu particle powder. Shear strength required for separating the bonded discs was 27.9 ± 3.9 for Cu discs, 28.1 ± 4.1 for Ni/Cu discs, and 13.8 ± 2.6 MPa for Ag/Ni/Cu discs. Epitaxial crystal growth promotes on the discs with a good matching for the lattice constants between metallic nanoparticles and metallic disc surfaces, which leads to strong bonding. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献